Amplifying apparatus for use with telephones



y 1953 ,o. J. FERRIERA 2,639,329

muwmc APPARATUS FOR use: wrm TELEPHONES Filed larch 27, 1 951 2 Sheets-Sheet 1 F A E Y :5 i E i. IT mmtor:

' In! John Immhm-nayy 1953 I DQ J. FERRIER V 2,639,329

AMPLIFYING APPARATUS FOR WITH TELEPHONES Filed larch 27, 1951 2 Sheets-Sheet 2 IIWEIT m 3 DAVID JOHN FEBRIHI 5 AT! GREY i Patented May 19, 1953 UNITED STATES PATENT 01m AMPLIFYING APPARATUS FOR USE WITH TELEPHONES David J. Ferrier, St. Kilda, Victoria, Australia Application March 27, 1951, Serial No. 217,722

6 Claims. (C1. 179-1) This invention relates to an amplifying apparatus for use with telephones whereby the incoming call is amplified and the call answered without the necessity of listening to or speaking di rectly into the telephone receiver or transmitter.

In using hand-set telephones of the standard type it is frequently inconvenient to hold the line until the caller or party being called transmits their message, accordingly considerable ad vantages would arise, particularly in the saving of time, if it were possible to receive an amplified reproduction of the incoming message without holding the receiver or in any way altering or interfering with the standard telephone equipment, which latter practice seldom meets with the approval of the authorities controlling public telephone communication systems.

The principal objective of the present invention is to provide an amplifying apparatus for use with telephones whereby an amplified reproduction of the incoming message is achieved without requiring any alteration to standard telephone equipment.

A further objective of the invention is to provide a mechanical voice intensifier with the apparatus to enable answers to the incoming message to be directed to the telephone transmitter.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

Although the novel features which are believed to be characteristic of this invention will be more particularly pointed out in the claims appended hereto, the invention itself may be better understood by' referring to the following description, taken in connection with the accompanying drawings, in which a specific embodiment thereof has been set forth for purposes of illustration. In these drawings:

Figure l is a front elevation of the apparatus showing the telephone transmitter-receiver hand-set in operative position on the apparatus;

Figure 2 is a view in side elevation of Figure 1 from the left hand side;

Figure 3 is a rear elevation with the cover plate removed;

Figure 4 is a view in side elevation from the right hand side of Figure 1; and

Figure 5 is a plan view.

Figure 6 is a detail perspective view partly in section of the hand-set rest and signal pick-up.

Figure 7 is a diagrammatic view of the circuit for amplifying the signals induced in the pick-up. Figure 8 is a vertical sectional view of the hand-set support constructed according to the present invention and showing a switch arrangement which is alternative to that shown in Figure 6.

As illustrated in the drawings, the apparatus comprises a metal casing l9 having on the top and adjacent one end thereof a cradle indicated generally at H to receive the earpiece l2a of a telephone transmitter-receiver hand-set 12. The mouthpiece of the transmitter lib of the handset fits into an opening [-3 in the end Wall Ilia of the casing Ill. The opening i3 is provided in a rubber or like grommet it which ensures that the mouth-piece of the transmitter lib fits snugly into the opening [3. The inner portion iii of the grommet M- is connected to the inner end of a horn It which may be a tortuous exponential horn or other suitable shape. The outer end of the horn i6 registers with an opening ll in the front face lb of the casing It. The opening I! may be covered with agauze I B or screened in any suitable manner.

The other end Hie of the casing 16 is provided with a louvered opening l9 behind which is a loud-speaker 23. The louvres I911 of the opening as are arranged to be outwardly inclined from the centre louvre to provide sound diffusion and assist in the prevention of acoustical feedback. An opening 2! (shown in broken lines in Figure 3) is provided in the rear of the casing iii to assist in the elimination of acoustic feed-back to prevent resonance within the casing and to provide ventilation.

Also positioned in the casing H3, rearwardly of the loud-speaker 2-0, is a four valve amplifier in-' dicated generally at 22. Electrical energy may be H in which the ear-piece iii-a rests, comprises a bell-crank member moulded from suitable synthetic plastic material and se-' cured to the top of the casing H The upstanding arm 25 of the bell-crank contains an e1ectrical pick-up device comprising two series-com nected coils of fine gauge wire wound on ironcored bobbins and covered by insulating plates 25, 27. The lower arm 28 of the bell crank contains a recess 29 which allows the ear-piece to move automatically to a central position when placed on the bell crank as shown in Figure 1. The lower portion Ha of the bell crank is made hollow for a purpose referred to hereinafter. The bell crank is pivotally mounted on the casing IE! by means of flat pivot projections 39 which are moulded integrally with the bell crank, and project laterally from each side thereof. The pivot projections 30 extend laterally from the bell crank underneath the top of the casing II] and are supported on each side by a U-shaped bracket 3I having outwardly directed flanges 3Ia which are attached to the underside of the top of the casing II by bolts 32. For the sake of clarity, only one half of the U-shaped bracket 3I is shown in Figure 6. One of the bolts 32 also carries a pair of leaf contacts 33, 34 which are mounted between strips of insulating material 35. The free end of the upper contact 33 is biased uywardly so as to be normally clear of the contact 34- but projects under the bell-crank so that depression of the latter by the weight of the telephone hand-set, forces the contact 33 into engagement with contact 24. The switch formed by contacts 33, 34 is located in circuit with the amplifier 22 so that the amplifier is energized only when the switch is closed.

Soft rubber material 36, preferably of the type known as latex foam, is disposed above and below the projections 30 so that the bell crank is entirely supported onrubber and does not make contact with any metallic part of the apparatus except the leaf spring 33 of the switch. The recess 29 is positioned in the lower arm 28 so that the center of ravity of a telephone hand-set sup ported on the lower arm will be displaced from the projections 30 to provide a rocking moment about said projections. The mounting of the projections 33 enables the bell crank to move with a limited angular movement about the pivot as well as permitting limited vertical and horizontal displacement and limited lateral rocking movements. When th ear-piec I2a of a telephone hand-set is placed in the cradle I I so that the weight of the hand-set is mainly supported by the lower arm 28, the bell crank is pivoted in an anti-clockwise direction, as viewed in Figure 1, and in the clockwise direction, as viewed in Figure 6, so that the arm 25 moves into close engagement with the ear-piece and is retained in that position. The various possible movements of the bell crank referred to above ensure that the bell crank accommodates itself to any particular ear-piece so that the coils of the pickup device are held as close as possible to the front face of the ear-piece.

Upon depression of the arm 28, the switch contacts 33, 34 are closed in the manner described above, thus energizing the filaments of the resistance coupled valves 31, 38, 39 and 4B of the amplifier hook-up 22 diagrammatically shown in Figure 7.

In use of the apparatus above described, the hand-set I2 of the telephone is placed with the ear-piece I2a in the cradle II and the mouthpiece of the transmitter I2b in the opening I3 as above described, when it is desired to receive or transmit a message through the telephone.

The positioning of the hand-set in this manner effects closing of the switch contacts 33, 34 by depression of the arm 28, to energize the filament circuit of the amplifier 22, the output of which is adjusted by the volume control 40 thus permitting conversations to be adjusted as required.

Magnetic variations caused by an incoming messag in the telephone receiver pole pieces (not shown) induce an E. M. F. in the coils of the pick-up device whichis imparted to the grid circuit of the valve 31 of the amplifier 22, such signal being amplified and reproduced by the loud-speaker 20.

As telephone ear-pieces vary slightly in dimensions the adjusting movements permitted by th pivot mounting of the bell crank carrying the pick-up coils, enable the air-gap between the said coils and the pole pieces to be as small as possible, thus assisting the coils in picking up the incoming message in the hand-set I2. The advantages of using a pick-up device operated by the magnetic variations of a telephone ear-piece are such that the pick-up device is not responsive to sound and consequently the difiiculty of acoustic feed-back into the receiver is overcome. In addition, the rubber mounting of the cradle I I and the seating of the mouth-piece I2b in the rubber or like grommet I4 eliminates the ffect of mechanical vibration transmitted through the casing.

It has been found by experiment that the arrangement of the outwardly deflected louvres I9a of the loud-speaker opening I9 play an important part in the elimination of acoustic feed-back. The opening 2I at the rear of the casing I0 may also assist in eliminating feed-back and resonance within the casing as well as directing the sound from the loud speaker in more than one direction.

An answer to an incoming message can be effected by speaking into the horn I6 which provides mechanical intensification of the voice for transmission through the telephone transmitter I2b. The horn IE5 is preferably designed to follow an exponential curve in order to provide an efiicient sound intensifying device. As a further measure to avoid internal resonance, the interior of the cabinet may be lined with felt or other sound-absorbing material.

If the current and voltage required by the valves of the amplifier are such that a switch having leaf-type contacts is not suitable for use in controlling the operation of the amplifier, a mercury switch may be used instead. Figure 8 shows a cradle II comprising a bell crank mem- Iber having at least the lower portion Ila thereof hollowed out and including an upstanding arm 25 and a lower arm 28. The lower arm 28 is formed with a recess 29, as in the previously described embodiment, for receiving the ear-piece of a telephone hand-set which is to be supported. The arm 25 carries two series-connected coils M and 42 of fine gauge wire wound on iron-cored bobbins and covered by insulating plates 26 and 21. Circuit connections 46 are provided for the coils M and 42 and pass through a suitable opening 45 in the base of the lower arm 28. A mercury switch 43 in series with the amplifier is mounted within the hollow lower portion IIa of the bell-crank with the leads 44 from the contacts of the switch 43 also passing through the opening 45.

The mercury switch 43 is disposed within the bell-crank so that the contacts thereof are electrically separated from each other when the bell crank is in its normal position (Figure 8), that is, in the position which th bell crank assumes without a hand-set supported thereon. When however the bell crank is tilted under the weight of a telephonehand-set, the corresponding angular movement of the mercury switch is arranged to energize the amplifier as is effected by the closing of the leaf contacts 33, 34 previously referred to. When a mercury switch is used, the leaf contacts 33, 34 can of course be eliminated.

An apparatus as above described is relatively economical of manufacture and provides an efficient telephone accessory which has the particular advantage that in use, no interference with amaze existing telephone equipment is necessary and by reason of compactness and portability may be used with any telephone of the hand-set type without the necessity of obtaining the approval of the telephone communication autorities.

I claim:

1. In amplifying apparatus for use with atelephone instriunent of the hand-set type having a mouth-piece and an ear-piece; a cabinet having a vertical exterior wall, a two-armed bell crank member, flat pivot projections extending laterally from one arm of said bell crank member, supporting brackets for said projections secured to said cabinet adjacent the upper portion of said vertical wall, resilient packing material between said fiat pivot projections and said supporting brackets to cushion resiliently the projections in the brackets, an inductive pick-up device mounted in the other arm of the bell crankmember, said one arm of the bell crank member being formed to support the telephone ear-piece whereby the mouth-piece hangs downwardly below said bell crank member and the arm of the bell-crank member carrying the inductive pickup device is urged by the weight of the telephone instrument to lie against the front face of the ear-piece, said vertical wall of the cabinet having an opening into which the mouth-piece of the hand-set projects when the ear-piece of the telephone instrument is supported by said bell crank member, a resilient seating member for the mouth-piece of the telephone instrument in said opening in the vertical Wall of the cabinet, an amplifier in the cabinet, electric circuit connections between said amplifier and said inductive pick-up device, a loudspeaker in the cabinet, electric circuit connections between the amplifier and the loudspeaker and a tubular member in the cabinet positioned to pick up local sound and to conduct the same to said opening in the vertical wall of the cabinet for communication to the mouthpiece of a telephone instrument positioned in said opening.

2. In amplifying apparatus for use with a telephone instrument of the hand-set type having a mouth-piece and an ear-piece; a cabinet, a two.- armed bell crank member, flat pivot projections extending laterally from one arm of said bell crank member, supporting brackets for said projections secured to said cabinet, resilient packing material between said flat pivot projections and said supporting brackets to cushion resiliently the projections in the brackts, an inductive pick-up device mounted in the other arm of said bell crank member, said one arm of the bell crank member being formed to support the telephone ear-piece whereby the mouth-piece hangs downwardly below said member and the arm of the bell-crank support carrying the inductive pick-up device is urged by the weight of the telephone instrument to lie against the front face of the ear-piece, said cabinet having an opening positioned to receive the mouth-piece of the telephone instrument when the ear-piece of the instrument is supported on the bell crank member, a resilient grommet positioned in said opening to cushion said mouth-piece, an amplifier in the cabinet, electric circuit connections between the amplifier and said inductive pick-up device including switch means operable in one sense to energize said amplifier when the telephone instrument is placed on the bell crank member and operable in the opposite sense to de-energize said amplifier when the telephone instrument is removed from the bell crank member, a loudspeakerin the cabinet. electric connections between the amplifierend the loudspeaker and acoustical amplifier positioned to pick up local sound and to conduct the same to said opening in the cabinet for ccmmimication to the mouth piece of a telephone instrument positioned in said opening.

3. In amplifying apparatus for with a telephone instrument of the hand-set type having a mouth-piece and an can-piece; a cabinet having a vertical exterior wall, :a two armed bell crank member, flat pivot projections having upwardly and downwardly racing fiat sides pro- J'ecting laterally from one arm or" said bell member, resilient packing material above low said projections to cushion the projections, the bell crank member being supported entirely by the said projections, brackets secured to said cabinet to support said resilient packing material, an inductive pick-up device mounted in the other arm of said bell crank member, said one arm of the bell crank member being formed to support the telephone ear-piece whereby the mouth-piece hangs downwardly below said "bell crank member with its center of gravity displaced from said pivot projections so that the arm of the bell-crank member carrying the inductive pick-up device is urged by the weight of the telephone instrument to lie against the front face of the ear-piece, said vertical wall of the cabinet having an opening into which the mouth-piece of the hand-set projects when the ear-piece of the telephone instrument is supported by said bell crank member, an amplifier in the cabinet, electric circuit connections between said ampliher and said inductive pick-up device including normally open switch contacts mounted beneath said bell crank member and disposed in relation thereto whereby they are closed to energize the amplifier when said bell crank member is rocked by placement of the telephone instrument on the bell crank member, a loudspeaker in the cabinet, electric circuit connections between the amplifier and the loudspeaker and an acoustical amplifier positioned to pick up local sound and to conduct the same to said opening in the cabinet for communication to the mouthpiece of a telephone instrument placed in said opening.

4. In amplifying apparatus for use with a telephone instrument of the hand-set type having a mouth-piece and an ear-piece; a cabinet, a bell-crank member having an upper arm and a lower arm, an inductive pick-up device mounted in the upper arm of the bell crank member, the lower arm of the bell crank member being formed to support the telephone ear-piece whereby the mouth-piece hangs downwardly below said memher and the upper arm of the bell-crank member is urged by the weight of the telephone instrument to lie against the front face of the ear-piece, said cabinet having an opening positioned to receive the mouth-piece of a telephone instrument when the ear-piece of the instrument is supported on said lower arm of the bell crank member, a resilient grommet positioned in said opening to cushion said mouth piece, pivot projections extending laterally from the bell crank member, support means on said cabinet receiving said projections and resiliently resisting rotation of the bell crank member about said pivot projections whereby the bell crank member has only a limited angle of movement about said projections under the influence of the weight of the telephone instrument and will return to its original position when the telephone instrument is removed from.

the bell crank member, an amplifier in the cabinet, electric circuit connections between the amplifier and said inductive pick-up device including switch means responding to rocking of said bell crank member and operable in one sense to energize said amplifier when the telephone instrument is placed on the bell crank member and operable in the opposite sense to deenergize said amplifier when the telephone instrument is removed from the bell crank member, a loudspeaker in the cabinet, electric circuit connections between the amplifier and the loudspeaker and an acoustical amplifier positioned to pick up local sound and to conduct the same to said opening in the cabinet for communication to the mouth-piece of a telephone instrument positioned in said opening.

5. In amplifying apparatus for use with a telephone instrument of the hand-set type having a mouth-piece and an ear-piece; a cabinet, a hollow two-armed bell crank member, flat pivot projections extending laterally from said bell crank member, supporting brackets for the said projections secured to said cabinet, resilient packing material between said fiat pivot projections and said supporting brackets to cushion resiliently, the projections in the brackets, an inductive pick-up device mounted in one arm of the bell crank member, the other arm of the bell crank member being formed to support a telephone earpiece whereby the mouth-piece hangs downwardly below said member with the center of gravity of the telephone instrument displaced from said pivot projections so that said bell crank member is rocked and the arm of the bell-crank memberv carrying the inductive pick-up device is urged by the weight of the telephone instrument to lie against the front face of the ear-piece, said cabinet having an opening positioned to receive the mouth-piece of the telephone instrumentwhen the ear-piece of the instrument is supported on the bell crank member, a resilient grommet positioned in said opening to cushion said mouth-piece, an amplifier in the cabinet,

electric circuit connections between the amplifierv and said inductive pick-up device including mercury switch means disposed within said hollow bell crank member to rock with the latter and operable in one sense to energize said amplifier when the telephone instrument is placed on the bell crank member and operable in the opposite sense to de-energizesaid amplifier when the telephone instrument is removed from the bell crank member, a, loudspeaker in the cabinet, electric circuit connections between said amplifier and said loudspeaker and an acoustical amplifier positioned to pick up local sound and to conduct the same to said opening in the cabinet for communication to a mouth-piece positioned in said opening.

6. In amplifying apparatus for use with a tele phone instrument of the hand-set type having a mouth-piece and an ear-piece; a cabinet, a hollow bell crank member having an upper arm and a lower arm, an inductive pick-up device mounted in said upper arm of the bell crank member, the lower arm of the bell crank member being adapted to support the telephone earpiece whereby the mouth-piece hangs downwardly below said member and the upper arm of the bell crank member is urged by the weight of the telephone instrument to lie against the front face of the ear-piece, said cabinet having an opening positioned to receive the mouth-piece of the telephone instrument when the ear-piece of the instrument is supported on the lower arm of the bell crank member, a resilient grommet positioned in said opening to cushion said mouthpiece, pivot projections extending laterally from the bell crank member in locations displaced from the center of gravity of a telephone instrument supported on said lower arm of the bell crank member, support means adapted resiliently to resist rotation of the bell crank member about said pivot projections whereby the bell crank member has only a limited angle of movement about said projections under the influence of the weight of the telephone instrument and returns to its original position when the telephone instrument is removed from the bell crank member, an amplifier in said cabinet, electric circuit connections between said amplifier and said inductive pick-up device including mercury switch means disposed within the hollow bell crank member for movement with the latter and operable in one sense to energize said amplifier when the telephone instrument is placed on the bell crank member and operable in the opposite sense to ole-energize said amplifier when the telephone instrument is removed from the bell crank member, a loudspeaker in said cabinet, electric circuit connections between said amplifier and loudspeaker and an acoustical amplifier positioned to pick up local sound and to conduct the same to said opening in the cabinet for communication to the mouth-piece of a telephone instrument positioned in said opening.

DAVID JOHN FERRIER.

References Cited in the file of this patent UNITED STATES PATENTS 

